1. Field of the Invention
The present invention relates to mobile station equipment that is carried on amobile unit or in a mobile vehicle or carried by a subscriber to offer communications services to the subscriber. The invention also relates to base station equipment for forming a wireless zone in a region where a mobile station can be positioned and providing channel control in the wireless zone. Furthermore, the invention relates to an exchange that associates with this base station equipment and performs call processing. In addition, the invention relates to a mobile communication system composed of such mobile station equipment, base station equipment, and exchange.
2. Description of the Related Art
In recent years, mobile communication systems have become rapidly widespread because of competition among communication service providers and liberalization of the market. Therefore, subscribers receive various kinds of communication services through in-vehicle terminals, as well as through transportable terminals.
FIG. 14 illustrates an example of configuration of a mobile communication system.
In this figure, mobile station equipment 80 is located within a wireless zone 82 formed by radio base station equipment 81, which is connected with radio control station equipment 83 through a communication link 81L. An exchange 84 connected with switching networks and home location registers (none of which are shown) is connected with the radio control station equipment 83 through a communication link 84L.
The mobile station equipment 80 comprises: antennas 85M-1, 85M-2; a TX/RX part 86M connected with the loading points of these antennas; a processor 87M having input/output ports connected with the control terminals of the TX/RX part 86M and with the output of a speedometer (not shown); a microphone 88 and a receiver 89 both connected with the modulation input and demodulation output, respectively, of the TX/RX part 86M; and a operation/indication part 90 connected with given input/output ports of the processor (CPU) 87M.
The radio base station equipment 81 comprises: an antenna 85B; a TX/RX part 86B connected with the loading point of the antenna 85B; a transmission path interfacing part 91B connected with the modulation/demodulation terminal of the TX/RX part 86B and with one end of the communication link 81L described above; and a processor (CPU) 87B, whose input and output ports of the processor 87B are connected with the control terminals of the TX/RX part 86B and of the transmission path interfacing part 91B.
The radio control station equipment 83 comprises a transmission path interfacing part 91C and an exchange interfacing part 92 both cascaded between the other end of the communication link 81L and one end of the communication link 84L, and a processor (CPU) 87C whose input and output ports are connected with the control terminals of the transmission path interfacing part 91C and of the exchange interfacing part 92.
The exchange 84 comprises: a radio interfacing part (RI) 93 directly connected with the other end of the transmission path 84L; a switch 94 having ports connected with the radio interfacing part 93 and the aforementioned switching networks, respectively; and a processor (CPU) 87E having communication ports connected with the aforementioned radio interfacing part 93, the switch 94, and home location register, respectively.
In the mobile communication system of the construction described so far, the TX/RX part 86B incorporated in the radio base station equipment 81 forms the wireless zone 82 under control of the processor 87B and interfaces, through the transmission path interfacing part 91B, with the communication link 81L and the radio channel both forming the wireless zone 82.
In the radio control station equipment 83, the processor 87C cooperates with the processor 87B disposed opposite to the processor 87C through the transmission path interfacing part 91C, the communication link 81L, and the transmission path interfacing part 91B, and performs channel control of the wireless zone (radio channels).
The transmission path interfacing part 91C and the exchange interfacing part 92 interface the communication links 81L and 84L with each other, based on the procedure of the channel control performed by the processor 87C in this way.
In the exchange 84, the processor 87E performs, by associating with the processor 87C that is located opposite to the processor 87E through the radio interfacing part 93, the communication link 84L, and the exchange interfacing part 92, call processing of the following termination call, terminating from the switching networks to the mobile station equipment 80 and the originating calls of the mobile station equipment 80 that are identified by the radio interfacing part 93.
The call processing adapts to the aforementioned channel control. The originating calls may contain calls for location updating. This call processing contains setting and resetting of a speech path to the switch 94.
In the mobile station equipment 80, when a origination request a call containing a phone number is given by the operation/indication part 90, for example, the processor 87M transmits an origination call signal to a certain radio channel formed by the radio base station equipment 81, and performs the channel control by associating associates with the processor 87B incorporated in the radio base station equipment 81 and with the processor 87C incorporated in the radio control station equipment 83.
When the corresponding origination call is completed based on the procedure of the channel control, the TX/RX part 86M secures a full duplex communication path between the mobile station equipment 80 and the radio base station equipment 81 by matching the speech signal to be sent and received through the microphone 88 and the receiver 89 to the radio channel assigned by the processor 87C incorporated in the radio control station equipment 83 over the period during which the completed call persists.
The processor 87M obtains the speed of the local station given by the speedometer described above and judges whether this speed is greater or smaller than a given upper limit.
The processor 87B recognizes the period for which the speed exceeds the upper limit. During this period, the processor 87B refrains from performing processing that should be invoked as the aforementioned channel control in response to an origination request given by the operation/indication part 90 and/or a paging signal that is sent by the radio base station equipment 81 and addressed to the local station through the antennas 85M-1, 85M-2, and TX/RX part 86M. At the same time, the processor 87B refrains from performing processing associated with location updating that should be invoked based on the procedure of the channel control.
In particular, as long as the upper limit described above is predetermined to a preferable value while the mobile unit or vehicle carrying the mobile station equipment 80 is moving at a high speed, origination calls and response to terminating calls for which the operation/indication part 90 is operated in some manner are restricted. Furthermore, location updating that is a factor of the transition to a state in which a subscriber can perform such operations are permitted is prolonged.
Accordingly, accidents that would normally be caused by user's operation on the mobile station equipment 80 while the mobile station equipment 80 is moving at a high speed are prevented with high reliability.
The TX/RX part 86M monitors the field strength level of receiving waves that reached the antennas 85M-1, 85M-2 from the antenna 85B incorporated in the radio base station equipment 81. The TX/RX part 86M appropriately selects the receiving waves of greater field strength level from those receiving waves and thus maintains high the speech quality according to switching diversity. The receiving waves are not restricted to waves that reach the antennas 85M-1, 85M-2 through the radio channel used for speech.
In the conventional configuration described above, the output of the speedometer described above is connected with the corresponding input port of the processor 87M through a dedicated connector and so there is the possibility that the connector is intentionally removed by the driver or that the driver forgets reattaching the connector after once removed.
In particular, the mobile unit or vehicle carrying the mobile station equipment 80 is able to run at a high speed without attaching the connector and, therefore, prevention of the aforementioned accidents cannot be accomplished reliably due to lack of driver's safety mind or human errors.
Such inappropriate removal of the connector can be prevented certainly by incorporating dedicated hardware in the mobile station equipment 80 to measure the moving speed of the moving unit or vehicle instead of the speedometer and to inform the processor 87M of the moving speed.
However, this configuration lowers of the cost effectiveness of the mobile station equipment and increases the cost. Although this configuration may be applied to newly manufactured mobile station equipment, it is impossible to apply it to already operating mobile station equipment or to those kinds of mobile station equipment which are not operated but appear on the market.
Consequently, it has not been assured that the aforementioned accidents are prevented.